Q1. Describe some of the drawbacks that you might encounter when using traditional IP routing.

Answer: Hop-by-hop forwarding decisions are based on IP destination lookup. IP lookup is based purely on the destination unicast address. All packets bound for the same destination follow the same path. All routers require full routing information to forward packets reliably.

Q2. Why is Policy Based Routing (PBR) unsuitable for engineering traffic in a large network?

Answer: PBR is a hop-by-hop mechanism and, therefore, cannot determine the entire path that a packet takes from ingress to egress. PBR is not scalable on a large scale because of its hop-by-hop nature; it also degrades router performance.

Q3. What benefit does the separation of forwarding and control elements, through the use of labels, provide?

Answer: A change in the information (such as a label) that controls the forwarding of packets does not need to be communicated to all devices within the network.

Q4. Does every MPLS node need to run an IP routing protocol to exchange IP routing information with other MPLS nodes?